The goal of this study is to determine if psychosocial manipulations influence the progression to disease in rhesus macaques who have been inoculated with the Simian Immunodeficiency Virus (SIV), a close genetic relative of HIV. We aim to accomplish this goal by employing an archival methodology which will permit us to analyze data from approximately 300 SIV-infected monkeys. Data will be collected from four NIH-sponsored regional primate research centers where Simian Aids research with rhesus macaques is being conducted. After careful screening of potential subjects' records for inclusion in this analysis, data pertaining to rearing history, caging history, medical history, SIV inoculation, and clinical outcome will be extracted and analyzed using multivariate techniques. Our hypotheses, based on what few pertinent data exist, are that changes in housing occurring both before and after viral inoculation will be related to the latency to onset of various physical and hematological signs of disease. Of particular interest are those housing changes which involve separation from familiar companions, and those which involve introduction to unfamiliar companions. Support for our hypotheses would provide the basis for further developing this animal model for use in prospective investigations of the mechanisms by which a) psychosocial processes affect SIV disease progression, and b) psychosocial interventions delay onset of clinical disease. To date all data have been collected from the CRPRC, and two other RPRCs. Most of the data from these centers has been coded, and analysis will begin upon receipt and coding of the final data set.